If you drive through central Illinois, you'll quickly notice giant windmills in the distance. Drive by them often enough, and they'll become familiar landmarks that you almost look forward to seeing. I'm sure they're enormous, but I've never been close enough to one to really put it in perspective.
Looking through old photos, I found this picture of them:
A few months ago, we were flying home to Chicago. Our flight had been delayed by four hours and many people had re-booked to a different flight, so there wound up being lots of empty seats. I took a window seat for a change (normally I prefer the aisle). As we got close to Chicago, I was able to see the windmills from a much different viewpoint! Here's a zoomed-in section of a photo I took:
I thought it was neat to see them from above.